Extraction of water miscible organic dyes by reverse micelles of alkyl glucosides

The extraction of methyl orange or methylene blue from an aqueous phase to an organic phase of reverse micelles of alkyl glucosides was investigated. Dodecyl glucoside, a biodegradable and biocompatible surfactant, was employed as a kind of alkyl glucosides, since a stable Winsor II system consisting of the water-in-oil type microemulsion and aqueous phases was formed when an organic solution containing dodecyl glucoside was contacted with an aqueous solution. The water content in the reverse micellar organic phase increased with an increase in the concentration of dodecyl glucoside. The extraction ratio of dyes also increased with increasing the concentration of dodecyl glucoside. Furthermore, the extraction ratio of dyes was dramatically dependent upon the pH of an aqueous phase and temperature.     

Controlling the radiation degradation of carboxymethylcellulose solution

In this study, the effects of an irradiation on the viscosity of the carboxymethylcellulose (CMC) solution were investigated, and the methods to control the degradation of the CMC caused by an irradiation were developed. The viscosity of the CMC solution was decreased with an increase in the irradiation dose, but the extent of the degradation by an irradiation was found to decrease with an increase in the CMC concentration in the solution. The dependency of the irradiation sources showed that an electron beam radiation had degraded the CMC less severely than a gamma ray radiation. An addition of vitamin C as a radical scavenger to the solution was shown to be effective in preventing the decrease of the viscosity of the solution. Also, in the case of an irradiation at −70 °C, the decrease of its viscosity was efficiently inhibited. The degradation of CMC in the solution was confirmed by the molecular weight distribution.     

(Polyfluoro)silane-mediated generation of azomethine ylides from imines and their cycloaddition leading to N-heterocycles

The novel generation and cycloaddition of azomethine ylides from an α-(trimethylsilyl)imine using (polyfluoro)silanes is described. The method was successfully applied to an efficient one-pot process. Namely, an azaallyl anion, generated by abstraction of the hydrogen α to an imino nitrogen, was treated with a di- or trifluorosilane to give an azomethine ylide intermediate below room temperature. The generated 1,3-dipole was smoothly trapped with dipolarophiles to afford nitrogen-containing five-membered heterocycles in good yields.     

Prevention of evaporation of small-volume sample solutions for capillary electrophoresis using a mineral-oil overlay.

The suppression of evaporation of water from small volumes of sample solutions or reagents for capillary electrophoresis by the use of a mineral-oil overlay was investigated in affinophoresis applications, in which the affinity constant of a mutant protein of recombinant human galectin-1 to a lactose affinophore, a triply negative charged ion having a lactoside as an affinity ligand, was determined. When an injection was carried out from a minimum of 20 microL of an aqueous solution beneath the oil overlay, no oil contamination inside the capillary was observed, provided the capillary was cleanly cut so that the end was flat, and the polyimide coating had been removed for a distance of about 2 mm from the end. Affinophoresis was carried out using 20 microL of an affinophore solution covered with an oil overlay. The abnormalities in the electropherograms as the result of the evaporation of the water from the solution during storage prior to use in an automatic operation of a capillary electrophoresis instrument were suppressed, with respect to the formation of a base line gap, an increase in the detection time of a marker ion and an increase in the initial current. A solution in a vial could be used repeatedly for a longer period of time when overlaid with mineral oil than in the absence of an overlay. The use of a mineral-oil overlay is a simple but very efficient technique for solving the problem of the evaporation of water from small volumes of aqueous solutions for use in capillary electrophoresis.     

Compression induced chiral symmetry breaking of monolayers comprised of banana-shaped achiral molecules at an air-water interface: Williams-Bragg approach

Chirality of monolayers comprised of banana-shaped achiral molecules at an air-water interface was investigated theoretically, and a forming mechanism of chiral structure as an assembly of achiral molecules was argued. A model of such monolayers was constructed taking into account the short-range repulsive interaction between constituent banana-shaped achiral molecules, and the free energy density functional of the model was derived as a generalization of Williams-Bragg approach. It was predicted that chiral symmetry breaking occurs by monolayer compression, where two-dimensional characteristics of monolayers at an interface plays an important role in the formation of chiral structure by banana-shaped achiral molecules.     

A facile synthesis of phytosphingosine from diisopropylidene-D-mannofuranose

In the present study, an efficient method with a high overall yield for preparing phytosphingosine and an analogue was developed. Starting with commercially available 2,3;5,6-di-O-isopropylidene-d-mannofuranose, a variety of lipid moieties were incorporated to obtain phytosphingosine and an analogue. Through an eight-step manipulation, phytosphingosine was obtained with an overall yield of 57%.     

Channel shape effects on the solution-flow characteristics and the liquid/liquid extraction efficiency in polymer microchannel chips.

A polymer microchannel chip with a symmetrical or unsymmetrical zigzag-side-walled structure was fabricated by an imprinting method, and applied to study shape effects on solution flow characteristics as well as on the liquid/liquid extraction efficiency of an aluminium(III) chelate complex (Al-DHAB: DHAB = o,o'-dihydroxyazobenzene) in a microchannel chip. In an unsymmetrical zigzag-side-walled channel chip (us-channel), an oil/water interface was sinusoidal, while that in a symmetrical zigzag-side-walled channel chip (s-channel) was flat as long as the observation was made under an optical microscope. It was demonstrated that the efficiency of the water-to-oil (1-butanol) extraction of Al-DHAB in the microchannel was governed by the contact time between the two phases. As the most important results, furthermore, the extraction efficiency was higher in the us-channel, as compared with that in the s-channel, owing to the sinusoidal liquid/liquid interfacial structure and, therefore, to the high interfacial area between the two phases.     

Miniaturization of capillary electrochromatography using an ultrashort capillary column

The instrumentation for miniaturization of capillary electrochromatography was devised and an injection method for this apparatus was proposed. By using an ultra short capillary column (15 mm packed length, 36 mm total length, 75 microm inner diameter, packed with cation exchange supports), the separation of five biochemical compounds was performed within 1 min. The high separation efficiency of 9780 plates was achieved by using an ultrashort capillary column. The miniaturized instrumentation for capillary electrochromatography might be utilized as one of the possible methods in microfabricated analysis or in an alternative approach to it.     

Chiral recognition of borneol by association with zinc(II) and l-tryptophan in the gas phase

Chiral recognition of the racemic borneol was obtained in the gas phase by using electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) and electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTMS). Both single stage MS and tandem MS were employed for investigating the chiral recognition depending strongly on the stereochemistry of the ligands in the zinc(II)-l-tryptophan-borneol multimeric cluster ions. It was found that the type of acid which was used for adjusting the pH of the mixed solution played an important role in the chiral recognition, which was obtained when acetic acid or propanoic acid was used as an additive. No chiral recognition was observed using hydrochloric acid or formic acid. Furthermore, the nozzle potential was an important parameter for optimizing the discrimination of chirality. In tandem MS, the difference in intensity between two diastereomeric complex ions showed chiral recognition behavior. Such a difference could be determined by two approaches. One was using the fragment ion as an internal standard, the other was a new approach of using the isotopic form of parent complex ion as an internal standard.     

Simultaneous determination of serum uremic toxins, cations and anions and urea determination by post-column colorimetry using immobilized enzyme

A column-switching method which combines ion-exchange and ion-pair reversed-phase chromatography was developed for the determination of serum uremic toxins, cations and anions. Serum urea, which was poorly separated by reversed-phase chromatography, was analyzed using an immobilized-urease column and detected by post-column colorimetry. Apart from the simultaneous analysis, anion analysis using ion-pair reversed-phase chromatography on an ODS column was also developed. The origin of the system peak observed in anion analysis with an eluent containing phthalate has been clarified.     

无色孔雀绿光氧化反应的途径

前一篇文章已说明,无色孔雀绿(LMG)经光氧化生成孔雀绿(MG⁺)染料是一个复杂的光化学过程。萘加入反应溶液猝灭了LMG的激发态,但却使反应速率升高。对这一实验结果我们曾推断为:可能是由于萘与LMG之间发生了电子转移作用。本文将对这一推断作进一步实验论证,并将说明在没有电子受体参加时,LMG的光氧化主要通过其激发三线态途径进行。已得到的实验结果证明,我们的上述推断是正确的,现予以报道。     

The mechanism for palladium catalyzed carbonylation of cinnamyl chloride

In the palladium catalyzed alkoxycarbonylation of cinnamyl chloride two mechanisms play a role. An associative mechanism was observed at low pressure, while an insertion mechanism was observed at high pressure or when an excess of ligand was used. Several putative intermediates of the catalytic alkoxycarbonylation have been synthesized and characterized, such as 5c of which an X-ray crystal structure was obtained.     

Protrusion and deformation of an elastic particle at an advancing front interface

The response of an elastic particle to an extensional field close to an advancing liquid–gas interface in a capillary was examined both from an experimental and theoretical viewpoint. Experimental evidence is given on both the protrusion and deformation of an elastic particle at an advancing front interface. To interpret our experimental results, we followed and extended Hoffman's approach to the case of deformable particles. A hybrid approach was followed where the height of the bump was calculated theoretically as an equilibrium between capillary and drag forces for a given deformation of the particle, whereas the latter was supplied by an independent experimental measurement. For an elastic particle, the height of the bump goes through a maximum and further on decay almost linearly when plotted against the dimensionless parameter introduced by Hoffman. The difference between the theoretical prediction and the experimental data is discussed in relation to the asymmetry of the bump profiles observed in the experiment that could be responsible for a larger contribution of capillary forces from those calculated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1362–1374, 2003     

Microfabricated electroosmotic pump for capillary-based sequential injection analysis

A microfabricated electroosmotic pump with an integrated serpentine isolation channel was developed on a glass chip and applied to a capillary-based sequential injection analysis (SIA) system for an enzyme inhibition assay. The pump chip contains an anode reservoir, an ion-exchange membrane electric field decoupler (EFD) that also serves as a cathode reservoir, parallel pump channels and an isolation channel. A two-step etching process was adopted to etch the pump channels to a depth of 20 μm and the isolation channel to a depth of 90 μm. The pump flow rate was very stable: the relative standard deviation (RSD) of the pump rate was 1.9% for propulsion and 2.3% for aspiration. The pump chip was successfully applied to a capillary-based sequential injection analysis system with a confocal fluorescence detector. For repetitive analysis of a 13 μM fluorescein solution, an RSD of 0.6% was attained, which demonstrated the flow stability of the EOF pump. The system was then applied to an enzyme inhibition assay, the diethylenetriaminepentaacetic acid (DTPA) inhibition of the β-galactosidase-catalyzed hydrolysis of fluorescein di(β-d-galactopyranoside). Reproducible results (RSD<3.0%) were obtained.     

Cationic carbohydroxylation of alkenes and alkynes using the cation pool method

The reactions of an N-acyliminium ion pool with alkenes and alkynes gave gamma-amino alcohols and beta-amino carbonyl compounds, respectively, after treatment with H(2)O/Et(3)N. The present reaction serves as an efficient method for cationic carbohydroxylation of alkenes and alkynes. When vinyltrimethylsilane was used as an alkene, the reaction was highly diastereoselective and served as an access to an enantiomerically pure alpha-silyl-gamma-amino alcohol. [reaction: see text]     

Microscopic observation and characterization of the oil bridge between dehulled-roasted sesame seeds

The formation of an oil bridge between adhesive seeds was observed microscopically. The geometry of the oil bridge was affected by the shape of the adhesive seeds. The capillary force of the oil bridge was estimated from the image captured by the microscope. The average capillary force was 127 μN, which was five times higher than the average gravity of the seeds. It was observed that several oil bridges formed between two seeds. These results indicated an adequate ability of the seeds to adhere. The capillary force of the oil bridge increased with surface oil content. The probability of formation of an oil bridge increased with surface oil content when the surface oil content was above 0.63%. The probability of formation of an oil bridge markedly increased when sucrose was added to the seeds.     

Search for Non-Protein Protease Inhibitors Constituted with an Indole and Acetylene Core

A possible inhibitor of proteases, which contains an indole core and an aromatic polar acetylene, was designed and synthesized. This indole derivative has a molecular architecture kindred to biologically relevant species and was obtained through five synthetic steps with an overall yield of 37% from the 2,2′-(phenylazanediyl)di(ethan-1-ol). The indole derivative was evaluated through docking assays using the main protease (SARS-CoV-2-M^pro) as a molecular target, which plays a key role in the replication process of this virus. Additionally, the indole derivative was evaluated as an inhibitor of the enzyme kallikrein 5 (KLK5), which is a serine protease that can be considered as an anticancer drug target.     

CdS量子点与曙红Y间的荧光共振能量转移研究

在水溶液中,量子点与有机荧光染料之间可能发生荧光共振能量转移(FRET)。本文以发射波长470nm的Cd S量子点为供体,曙红Y为受体,建立了Cd S量子点-曙红Y的FRET体系,研究了该体系的FRET参数。该体系受体供体数目比为8,猝灭效率为45.6%,增强效率为20.1%;供体-受体间的距离为4.4nm;临界能量转移距离为2.4nm。     

Analysis of taurine in feline plasma and whole blood by liquid chromatography with fluorimetric detection and confirmation by thermospray mass spectrometry

A liquid chromatographic method with fluorimetric detection was developed to measure taurine (2-aminoethanesulfonic acid) in feline plasma and whole blood. Plasma or lysed whole blood was diluted with a mixture of acetonitrile-methanol-triethylamine-water (25:22:3:50, v/v), filtered through a 10,000 dalton exclusion filter and derivatized with dansyl chloride for 30 min at room temperature. Dansyl taurine was separated from other compounds by reversed-phase liquid chromatography using an octadecyl column and a methanol-acetic acid-triethylamine (30:0.5:0.025, v/v) aqueous mobile phase. The effluent was monitored fluorimetrically at an excitation wavelength of 329 nm and an emission wavelength of 530 nm. The presence of mono-dansylated taurine in feline plasma was confirmed by thermospray mass spectrometry. The limit of detection was 16 nmol/ml and the detector response was linear from 40 to 4000 nmol/ml taurine.     

Concise Construction of the ACDE Ring System of Calyciphylline A Type Alkaloids by a [5+2] Cycloaddition

A concise route for construction of the ACDE ring skeleton in calyciphylline A type alkaloids was developed using an intramolecular [5+2] cycloaddition reaction of an oxidopyrylium species bearing a tetrasubstituted olefin. Key to the success of this reaction was the combination of acid and base, which accelerated the construction of this skeleton containing a spiro ring and vicinal quaternary carbon centers. The resultant tricyclic ADE ring compound was converted to an ACDE ring model through C−H oxidation and an aza-Wittig reaction.